1. Field of the Invention:
The present invention relates to lawn mowing and mulching devices. More particularly, the present invention relates to a cutter head for use with a non-rotary, power lawn mower.
2. Discussion of Background:
Lawn mowers are well known devices used for cutting grass to maintain the appearance of an area. There are many types of lawn mowers, including rotary mowers and reel mowers. Lawn mowers featuring additional functions, such as mulching, collecting grass clippings, and the like, are also well known. Additionally, many different cutting blades or cutter heads are known for use with lawn mowing devices.
The most widely known lawn mower in use is the power rotary lawn mower having a single rotating blade with cutting edges at opposing distal ends of the blade. The cutting blade rotates at high speed within a circular housing to both cut the grass and create an upward draft to urge the blades of grass to stand upward for better cutting. The power mower housing functions to prevent injury to the user and to control the direction of discharge of grass clippings and other debris encountered during mower operation.
Normally, the cutting blade is centrally mounted on a shaft extending vertically through the housing from a gasoline or electric powered motor secured on the top of the housing. The motor causes the cutting blade to be rotated at high speeds, causing the grass immediately under the housing to be clipped.
Different rotary cutting blade configurations for power lawn mowers are used for a variety of reasons. For example, Burnell, in U.S. Pat. No. 5,019,113, discloses a rotary lawn mower blade assembly having easily detachable replacement blades. Mensing, in U.S. Pat. No. 4,532,708, discloses a blade assembly with a plurality of cutting segments arranged end to end for improved cutting. Also, in U.S. Pat. No. 3,964,243, Knipe features a rotary cutting blade with detachable tines used to blow grass clippings from the mower path.
Mullet et al, in U.S. Pat. No. 4,916,887, discloses a rotary mulching mower. The mower has a plurality of cutting blades rotatably positioned in a housing for producing mulch. Each cutting blade rotates through a different plane within the housing for cutting the grass clippings into a fine mulch.
The most significant problem with conventional rotary mowers is the inherent danger presented by a high-speed whirling blade. The blade is a direct threat if the user comes into contact with it, and an indirect threat if it propels an object from the housing. Furthermore, since the blade must be exposed to the grass, even the housing that covers it to protect the user is of no help if the mower overturns. Numerous safety features attempt to minimize the threat of direct and indirect injury from the blade.
Several problems exist with current rotary lawn mowers having rotary blades. Rocks, limbs, roots and other foreign debris entering the housing can damage the rotary blades or be suddenly propelled from the housing. Also, the blades become extremely dull and tend to rip and tear the grass rather than cut it cleanly. In sandy soil, the blades erode very rapidly. Thus, the blades have to be frequently replaced or sharpened.
In tall grass, a conventional mower bends the grass as the mower housing passes over it. If the grass is very long, the housing will hold it to the ground so that it is not cut.
Another problem with current rotary lawn mowers is the relatively slow speed at which the mower can travel across a lawn or other grass area to be cut. Even when rotating at high speeds, a single blade with 2 cutting edges requires the lawn mower to travel at very low speeds. Thus, it takes a substantial amount of time to mow large areas of grass.
It is believed that no present lawn mowing device addresses these problems sufficiently.